package net.borderwars.util;


/**
 * User: ehubbard
 * Date: Oct 7, 2007
 * Time: 12:26:21 PM
 */
public class Geometry {

    final static int[] table = {
            0, 16, 22, 27, 32, 35, 39, 42, 45, 48, 50, 53, 55, 57,
            59, 61, 64, 65, 67, 69, 71, 73, 75, 76, 78, 80, 81, 83,
            84, 86, 87, 89, 90, 91, 93, 94, 96, 97, 98, 99, 101, 102,
            103, 104, 106, 107, 108, 109, 110, 112, 113, 114, 115, 116, 117, 118,
            119, 120, 121, 122, 123, 124, 125, 126, 128, 128, 129, 130, 131, 132,
            133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 144, 145,
            146, 147, 148, 149, 150, 150, 151, 152, 153, 154, 155, 155, 156, 157,
            158, 159, 160, 160, 161, 162, 163, 163, 164, 165, 166, 167, 167, 168,
            169, 170, 170, 171, 172, 173, 173, 174, 175, 176, 176, 177, 178, 178,
            179, 180, 181, 181, 182, 183, 183, 184, 185, 185, 186, 187, 187, 188,
            189, 189, 190, 191, 192, 192, 193, 193, 194, 195, 195, 196, 197, 197,
            198, 199, 199, 200, 201, 201, 202, 203, 203, 204, 204, 205, 206, 206,
            207, 208, 208, 209, 209, 210, 211, 211, 212, 212, 213, 214, 214, 215,
            215, 216, 217, 217, 218, 218, 219, 219, 220, 221, 221, 222, 222, 223,
            224, 224, 225, 225, 226, 226, 227, 227, 228, 229, 229, 230, 230, 231,
            231, 232, 232, 233, 234, 234, 235, 235, 236, 236, 237, 237, 238, 238,
            239, 240, 240, 241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 246,
            246, 247, 247, 248, 248, 249, 249, 250, 250, 251, 251, 252, 252, 253,
            253, 254, 254, 255
    };

    public static int distanceSquared(int x, int y, int xx, int yy) {
        return ((xx - x) * (xx - x)) + (yy - y) * (yy - y);
    }

    public static int distance(int x, int y, int xx, int yy) {
        return sqrt(((xx - x) * (xx - x)) + (yy - y) * (yy - y));
    }


    public static int whenTheyMeet(int x, int y, int vx, int vy, int xx, int yy, int vxx, int vyy, int colissionRadius) {
        int startDistance = distance(x, y, xx, yy);  // at time 0                         (0, startDistance)
        int distancePrime = distance(x + vx, y + vy, xx + vxx, yy + vyy); // at time 1    (1, distancePrime)
        // see if they got closer -- or even stayed identical..
        if (distancePrime >= startDistance) {
            return (-1); // i.e. not in our future!
        }
        // now the goal is to get distance = m * time + b --  We can use 0,startDistance above.  That nice 0
        // will cancel out the M and ends up showing that B and startDistance are the same.. hey.. who woulda thought?
        //  Now that we have B (startDistance)..  distance = M * time + startDistance
        //  subtract startDistance from both sides
        //  (distance - startDistanace) = M * time
        //  divide both sides by M
        // (distance - startDistance)/M = time
        return ((colissionRadius - startDistance) / (distancePrime - startDistance));

    }


    /**
     * A faster replacement for (int)(java.lang.Math.sqrt(x)).  Completely accurate for x < 2147483648 (i.e. 2^31)...
     *
     * @param x the number we'll find the square root of
     * @return the square root of x
     */
    static int sqrt(int x) {
        int xn;

        if (x >= 0x10000) {
            if (x >= 0x1000000) {
                if (x >= 0x10000000) {
                    if (x >= 0x40000000) {
                        xn = table[x >> 24] << 8;
                    } else {
                        xn = table[x >> 22] << 7;
                    }
                } else {
                    if (x >= 0x4000000) {
                        xn = table[x >> 20] << 6;
                    } else {
                        xn = table[x >> 18] << 5;
                    }
                }

                xn = (xn + 1 + (x / xn)) >> 1;
                xn = (xn + 1 + (x / xn)) >> 1;
                return ((xn * xn) > x) ? --xn : xn;
            } else {
                if (x >= 0x100000) {
                    if (x >= 0x400000) {
                        xn = table[x >> 16] << 4;
                    } else {
                        xn = table[x >> 14] << 3;
                    }
                } else {
                    if (x >= 0x40000) {
                        xn = table[x >> 12] << 2;
                    } else {
                        xn = table[x >> 10] << 1;
                    }
                }

                xn = (xn + 1 + (x / xn)) >> 1;

                return ((xn * xn) > x) ? --xn : xn;
            }
        } else {
            if (x >= 0x100) {
                if (x >= 0x1000) {
                    if (x >= 0x4000) {
                        xn = (table[x >> 8]) + 1;
                    } else {
                        xn = (table[x >> 6] >> 1) + 1;
                    }
                } else {
                    if (x >= 0x400) {
                        xn = (table[x >> 4] >> 2) + 1;
                    } else {
                        xn = (table[x >> 2] >> 3) + 1;
                    }
                }

                return ((xn * xn) > x) ? --xn : xn;
            } else {
                if (x >= 0) {
                    return table[x] >> 4;
                }
            }
        }

        throw new IllegalArgumentException("Attemt to take the square root of negative number");

    }


}
